Rod and cutting tool

Abstract

A rod, a cutting tool and a method for manufacturing a cutting tool are disclosed. In an embodiment, the rod may include a cemented carbide member containing WC and Co. The cemented carbide member may be elongated and include a first end portion and a second end portion in a longitudinal direction. The first end portion may have a Co content CoAC smaller than a Co content CoBC of the second end portion. The cemented carbide member may include a first portion on a side of the first end portion and a second portion on a side of the second end portion. The first portion may have a gradient S1 representing a change in a Co content per millimeter. The second portion may have a gradient S2 representing a change in a Co content per millimeter. The gradient S1 may be greater than the gradient S2.

What is claimed is: 
     
       1. A rod, comprising:
 a cemented carbide member containing tungsten carbide (WC) and cobalt (Co), the cemented carbide member having an elongated shape, and the cemented carbide member comprising:
 a first end portion in a longitudinal direction, the first end portion having a Co content Co AC ; 
 a second end portion in the longitudinal direction, the second end portion having a Co content Co BC , the Co content Co AC  being smaller than the Co content Co BC ; 
 a first portion on a side of the first end portion, the first portion having a gradient S 1  representing a longitudinal change in a Co content per millimeter; and 
 a second portion on a side of the second end portion, the second portion having a gradient S 2  representing a longitudinal change in a Co content per millimeter, the gradient S 1  being greater than the gradient S 2 . 
 
 
     
     
       2. The rod according to  claim 1 , wherein
 the Co content Co AC  is 0.2 to 7 percent by mass, and 
 the Co content Co BC  is 2 to 12 percent by mass. 
 
     
     
       3. The rod according to  claim 1 , wherein
 a ratio Co AC /Co BC  of the Co content Co AC  to the Co content Co BC  is 0.2 to 0.7. 
 
     
     
       4. The rod according to  claim 1 , wherein
 the first end portion comprises a central area and an outer periphery in a direction perpendicular to the longitudinal direction, and 
 the central area has a Co content higher than a Co content in the outer periphery. 
 
     
     
       5. The rod according to  claim 4 , wherein
 when the outer periphery has a Co content CO AO  of 0.1 to 6.5 percent by mass, a ratio Co AO /Co AC  of the Co content CO AO  to the Co content Co AC  is 0.1 to 0.9. 
 
     
     
       6. The rod according to  claim 1 , wherein
 the gradient S 1  is 0.2 to 1.0 percent by mass per millimeter, and 
 the gradient S 2  is 0 to 0.2 percent by mass per millimeter. 
 
     
     
       7. The rod according to  claim 1 , wherein
 the cemented carbide member further comprises
 a third portion disposed between the first portion and the second portion, the third portion having a gradient S 3 , the gradient S 3  being larger than the gradient S 1  of the first portion. 
 
 
     
     
       8. The rod according to  claim 7 , wherein
 the gradient S 3  is 2 to 50 percent by mass per millimeter. 
 
     
     
       9. The rod according to  claim 1 , wherein
 the first portion has a longitudinal length L 1 , 
 the second portion has a longitudinal length L 2 , and 
 a ratio L 1 /L 2  is 0.2 to 2. 
 
     
     
       10. The rod according to  claim 1 , wherein
 a diameter d A  of the first end portion is 2 millimeters (mm) or less, 
 a diameter d B  of the second end portion is 2 mm or less, and 
 a ratio L/d A  of a longitudinal length L of the cemented carbide member to the diameter d A  is 3 or more. 
 
     
     
       11. The rod according to  claim 10 , wherein
 a ratio d A /d B  of the diameter d A  to the diameter d B  is 1.02 to 1.20. 
 
     
     
       12. The rod according to  claim 1 , further comprising:
 a protrusion located on a first end face of the first end portion. 
 
     
     
       13. The rod according to  claim 12 , wherein
 the protrusion has a Co content smaller than the Co content Co AC  in the first end portion. 
 
     
     
       14. The rod according to  claim 13 , wherein
 a Co content Co CC  in a tip of the protrusion is 0.1 to 6 percent by mass, and 
 a ratio Co CC /Co AC  of the Co content Co CC  to a Co content Co AC  in a central area of the first end portion in a direction perpendicular to the longitudinal direction is 0.1 to 0.8. 
 
     
     
       15. The rod according to  claim 13 , wherein
 the Co content in the protrusion is higher than the Co content Co AC  in the first end portion. 
 
     
     
       16. The rod according to  claim 15 , wherein
 a Co content Co CC  in a tip of the protrusion is 3 to 14 percent by mass, and 
 a ratio Co CC /Co AC  of the Co content Co CC  to the Co content Co AC  in a central area of the first end portion in a direction perpendicular to the longitudinal direction is 1.2 to 3. 
 
     
     
       17. The rod according to  claim 12 , wherein
 the first end portion has a diameter d A , 
 the protrusion has a diameter d C  at a position of contact with the first end portion, and 
 a ratio d C /d A  of the diameter d C  to the diameter d A  is 0.5 to 0.9. 
 
     
     
       18. A cutting tool, comprising:
 a cemented carbide member containing tungsten carbide (WC) and cobalt (Co), the cemented carbide member having an elongated shape, and the cemented carbide member comprising:
 a first end portion in a longitudinal direction, the first end portion having a Co content Co AC ; 
 a second end portion in the longitudinal direction, the second end portion having a Co content Co BC , the Co content Co AC  being smaller than the Co content CO BC ; 
 cutting edges at least on a side of the first end portion; 
 a shank portion on a side of the second end portion; 
 a first portion on a side of the first end portion, the first portion having a gradient S 1  representing a longitudinal change in a Co content per millimeter; and 
 a second portion on a side of the second end portion, the second portion having a gradient S 2  representing a longitudinal change in a Co content per millimeter, the gradient S 1  being greater than the gradient S 2 . 
 
 
     
     
       19. A method for manufacturing a cutting tool, the method comprising:
 placing the rod according to  claim 1  randomly into a joining machine; 
 distinguishing the first end portion of the rod from the second end portion in the joining machine and arranging the rod in a predetermined direction; 
 placing the second end portion of the rod in contact with a shank and joining the second end portion to the shank; and 
 forming cutting edges in a portion of the rod including the first end portion. 
 
     
     
       20. A method for manufacturing a cutting tool, the method comprising:
 placing the rod according to  claim 14  randomly into a joining machine; 
 arranging the rod in a predetermined direction in the joining machine based on whether the protrusion is detected or the protrusion is not detected; 
 joining the second end portion of the rod to a shank; and 
 forming cutting edges in a portion of the rod including the first end portion.